Comparison of nuclear and non-nuclear techniques to measure the soil moisture content

Abstract

Soil moisture measurement helps to improve the soil water management for better irrigation scheduling and growing of appropriate crops. It is of prime importance to select the right methodology for soil water monitoring. Measuring soil moisture by gravimetric method is time consuming and difficult to apply for long-term studies. Therefore, accurate soil moisture measuring methods should be introduced. A study was conducted to compare the newly improved continuous type nuclear and non-nuclear soil moisture measuring techniques in Seibersdorf Austria during May - September 2002. The neutron probe was used as the nuclear technique for measuring soil moisture. Time Domain Reflectometry (TDR) meter and capacitance sensors (Diviner 2000 and EnviroSCAN)) were used to measure soil moisture as non-nuclear techniques. The suitability and advantages of each instrument were evaluated in a spring wheat field. The soil moisture measurements obtained by above mentioned instruments were compared with the standard gravimetric method. The results revealed that there was no significant difference in soil moisture values obtained by neutron probe method and Diviner 2000 method, compared to the soil moisture measurements obtained by gravimetric method. The good agreement could be due to the larger sphere of measurement of the neutron probe, making small spatial variability due to the in homogeneity of the soil. However, the EnviroSCAN and the TDR either over- or under-estimates soil moisture. The results revealed that both nuclear (neutron probe) and non-nuclear (Diviner 2000) techniques could be applied to measure moisture content of soil